Low-level audio output independent of windows master volume

I would like to send audio data to the jack output of the soundcard. There are several options but the volume is always depending on the volume settings in the OS, i.e. windows.

For my application, it is crucial to control the output level without being influenced by the volume settings of the operating system (e.g., the master-volume).

Finally, the solution should work in a standalone application built with MATLA App Designer.

Answer 1

[dpb]

To bypass the OS miixer and talk directly to the audio board you'll need something like <Sound Card Support from DataAcq TB>. Anything done with the builtin MATLAB sound functions goes through the OS mixer as you've already discovered.

You'll have to check about whether the functionality is compilable; I didn't look it up.

[Christoph Schmid]

Thank you for this valuable hint. I allready tried DataAcq TB and generated audio as in this example:

Generate Audio Signals - MATLAB & Simulink

Unfortunately, the output using directsound depends on the OS mixer settings.

[dpb]

I may have misinterpreted what the DAQ Audio doc implies -- it's now not clear to me that it does enable you to talk directly to the audio board itself.

I found <the following link> that maybe can help.

I've never messed around with PC audio so don't know for sure but I'd presume there's some Win32 API that would let one control the mixer level and thereby fix the amplitude gain, but one would have to write mex code to get to it I suspect.

May not be as simple as first led to believe...you might look at the Ford MoCo example use, that would seem to have to have been able to use absolute levels, maybe it will give clues.